Solvents for derivatives of cellulose and compositions produced thereby



Patented Feb. 9, 1932 UNITED STATES PATENT OFFICE WILLIAI HERB?!" F CUMBERLAND, mYLAHD, ASSIGNOR '1'0 CELL'NESE COB,-

PORATION OF AMERICA, A CORPORATION OF DELAWARE SOLVENT-8 10B DERIVATIVES OF CEIhLULOSE AND COIPOSITIONB PRODUCED Y No Drawing.

This invention relates to the production of solvents for cellulose derivatives from mix tures of liquids of which the individual components are not themselves solvents for said 5 cellulose derivatives, and relates more particularly to the use of solvent mixtures containing methylene chloride as one component thereof.

An object of my invention is to produce l a solvent for cellulose derivatives containing methylene chloride and alcohols, which alcohols have a boiling point that is higher than that of methyl alcohol or ethyl alcohol. A further object of my invention is to pro l5 duce a coating composition or plastic composition containing derivatives of cellulose and a solvent mixture comprising methylene chloride and relatively non-volatile alcohol. Further objects-of my invention will appear 29 from the following detailed description.

It is hown that methylene chloride and certain low boiling point alcohols, such as methyl alcohol or ethyl alcohol, form solvents for cellulose acetates. It is well known that both methyl and ethyl alcohols have a'latent solubility for cellulose acetate, i, e. they form solvents for cellulose acetates when mixed with other liquids, either hot or cold. Thus for example, hot benzene and eth 1 alcohol form a solvent for .most types 0' cellulose acetate. However, it has not reviously been noted that other alcohols havmg higher boiling points, have latent solubilities for cellulose acetate. In fact, these alcohols are generally regarded as strong precipitants for cellulose acetate. Thus the proportion of n-hutyl alcohol, which can be added to an acetone solution of cellulose without precipitation, is in general much less than the proportion of ethyl alcohol and the proportion of amyl alcohol is still less. I have discovered, however, that the various relatively non-vo1atile alcohols when mixed with methylene chloride form an excellent solventjor cellulose acetate.

In accordance with my invention I prepare a solvent for derivatives of cellulose, which solvent contains methylene chloride (CH Cl and a relatively non-volatile alcohol or a derivative thereof, and preferably one that 1928. Serial No. 291,704.

boils above 100 C. This invention may be used for all purposes, such as making liquid coating composition or lastic compositions containing derivatives 0 cellulose, or for removing films of such derivatives from surfaces coated therewith.

The alcohol used in making the solvent mixture may be a monohydric alcohol of the aliphatic series having more than two car cyclo hexanol (hexahydrophenol), or methyl cyclo hexanol may be mentioned.

Because this invention is particularly use ful in connection with the preparation of solutions or plastic compositions containing cellulose acetate, details will be given with respect to the use of the solvent mixtures in connection with cellulose acetate.

of cellulose esters, n-butyl alcohol and methylene chloride form a better solvent than a commonly used solvent such as acetone.

Thus, while an acetone soluble cellulose acetate gave a solution in acetone of which the clarity in certain arbitrary units was '8, a solution of the same concentration in methylene chloride and butyl alcohol mixture was much clearer, and inthe same arbitrary units was measured as 33.

The excellence of a mixture of methylene chloride and tertiary butyl alcohol as jud ed by the usual standards is shown b the act that, whereas the above mentione' cellulose acetate gave a solution in acetone ,with a .clarityof 8 and a viscosity of 2.8 measured in certain units, the clarity of a solution of equal concentration in methylene chloride and tertlary butyl alcohol was 34 andfthe ,i Judged by the usual standards of solubility viscosity 2.4; that is, the mixed solvent methylene chloride and tertiary butyl alcohol gave a solution with lower Viscosity and a higher clarity than a standard solvent such as acetone.

As an instance of the excellent solvent properties of a mixture of methylene chloride alcohols or their derivatives.

and ethylene glycol or its ethers, it is pointed out that a solution of cellulose acetate in methylene chloride and mono ethyl ether of ethylene gl col gave viscosities and clarities measureti inbertain arbitrary units of 4.1 and 31.5 respectively, while the same concentration of cellulose acetate in acetone gave corresponding values of 2.8 and 8.

The proportions of the mixtures of these nonsolvents which form solvents for cellulose acetate of both the chloroform soluble type and the acetone soluble type are from 90% by volume methylene'chloride and by volume of the above mentioned alcohols and derivatives, to by volume of methylene chloride and by volume of the These limiting proportions vary with various specimens of cellulose acetate and also quite considerably with the temperature. Thus, while the upper limit of mono ethyl ether of ethylene glycol that is advisable in a mixture of this ether and methylene chloride at 25 C. on a certain cellulose acetate is parts by volume; at 35 C., the proportion is parts by volume.

It is also possible to make a mixture of methylene chloride with two or more of the aforementioned alcohols, derivatiyes and cyclohexanols, such mixtures being made according to various important considerations such as cost, odor, rate of evaporation, etc.,

and solubility for other constituents which it may be desirable to add to the solution of cellulose acetate. Thus, for example in the preparation of lacquers, resins and softeners may also be added to the cellulose acetate solutions in the above mentioned solvent mix- 'ture, and due consideration should be given of cellulose derivatives lacquers, the above solutions may be used with or without the addition ofother solvents and diluents for the cellulose derivatives. These other solvents may take the form of high boiling but volatile solvents such as ethyl lactate, diacetone alcohol, tetrachlorethane or of a nonvolatile solvent, such as triacetin, diethyl phthlate, dibutyl tartrate, etc., which remains in the cellulose acetate film, and is commonly called a softener or plastifier.

Natural .or synthetic resins, such as are compatible with the cellulose acetate or other derivatives of cellulose may also be added to the solutions and may also be considered as high boiling point solvents which remain in the film.

In some technical applications, the amount of high boiling point solvents of this type which is added to the cellulose acetate is such that the addition of other volatile high boiling point solvents such as ethyl lactate, etc., production of a clear Example I The following is an example of a solution of an organic-ester of cellulose containing methylene chloride and a monohydric aliphatic acid.

Parts Cellulose acetate 10 Methylene chloride 70 Butyl alcohol 30 Example I I This is an exm'aple of use of ether of a glycol in the solvent mixture:

Cellulose acetate 20 Methylene chloride 60 Mono ethyl ether of ethylene glycol 40 E :mmple III The following is an example of a composition that contains a plastifier:

Parts Cellulose acetate 10 Methylene chloride 70 Tertiary butyl alcohol 30 Diethyl phthalate 2 Example IV The following is an example of a liquid coating composition containing a pigment:

Pigment 3 Parts till ac-gees Emple V The following is an example of the use of a cyclic alcohol:

Parts Ucllulose acetate 20 Methylenechloride 80 Uyclohexanol 20 Benzyl alcohol 10 prising methylene chloride and a relatively nonvolatile liquid selected from the group of aliphatic alcohols and their ethers having a hoiling point above 100 C.

3. A solvent for esters of cellulose comprising methylene chloride and a relatively nonvolatile aliphatic alcohol. 4. A solvent for esters of cellulose comprising methylene chloride and an aliphatic alcohol having more than two carbon atoms.

5. A solvent for esters of cellulose comprising methylene chloride and a relatively nonvolatile liquid selected from the group of prillyhydric alcohols and their aliphatic ct era.

in a solvent mixture cdmplrising methylene I chloride and an aliphatic alcohol having a boiling point above 100 C.

13. A composition of matter containin cellulose acetate at least partially dissolve in a solvent mixture comprising methylene chloride and a butyl'alcohol.

14. A compositmn of matter containing cellulose acetate at least partially dissolved in a solvent mixture comprisin methylene chloride and an aliphatic alco o1 havingimore than two carbon atoms.

15. A composition of matter containin a derivative of cellulose at least partially issolved in a solvent mixture comprisin methylene-chloride and a substance selecte from the group of polyhydric alcohols and their aliphatic others.

16. A composition of matter containin an organic ester of cellulose at least part1ally dissolved in a solvent mixture comprisin methylene chloride and a substance selecte from the group of polyhydric alcohols and I I their aliphatic ethers. r

17. A composition of matter containing cellulose acetate at least partially dissolved in a solvent mixture comprisin methylene chloride and a substance selecte from the group of polyhydric alcohols and their aliphatic ethers.

18. A composition of matter containing cellulose acetate at least partially dissolved in a solvent mixture comprising methylene chloride and ethylene glycol.

In testimony whereof, I have hereunto subscribed my name.

WILLIAM HENRY MOSS.

t. A solvent for cellulose acetate compris:

ing; methylene chloride and butyl alcohol.

7. A solvent for cellulose acetate comprising methylene chloride and ethylene glycol.

8. A solvent for cellulose acetate comprising methylene chloride and mono ethyl ether of ethylene glycol.

9. A composition of matter containing csters of cellulose at least partially dissolved in a solvent mixture comprisin meth lene chloride and. a relatively nonvo atile l1 uid selected from the group of aliphatic alco ols and their ethers.

l0. A composition of matter containing cellulose acetate at least partially dissolved in a solvent mixture comprising methylene chloride and a relatively nonvolatile liq 'd selectad from the group of aliphatic al ohols and their ethers.

ll. A compositioii of matter containing cellulose acetate at least partially dissolved in a solvent mixture comprising methylene chloride and mono ethyl ether of ethylene glycol.

12. A composition of matter containin cellulose acetate at least partially dissolv 

